javascript - 控制回调流程

Question

我有以下 Node.js 代码。

index.js

"use strict";
// Close dialog with the user, reporting fulfillmentState of Failed or Fulfilled

var service = require("./service.js");

function dispatch() {
  const op = service.createIncident("enterpriseID", "shortDesc", function(
    incidentNo
  ) {
    if (incidentNo) {
      console.log("Index.js ServiceNow Incident:" + incidentNo);
      var msg = "Thank you! Your  Number is " + incidentNo;
      console.log("end of flow");
    } else {
      console.log("Index.js ServiceNow Incident:" + incidentNo);
      msg = "Err";
      console.log("end of flow");
    }
  });
  console.log("done");
}

dispatch();

这是我的 service.js

var request = require("request-promise");
var servicenow = require("./configfile.json");

var snowURL = servicenow.url;
var snowUsername = servicenow.username;
var snowPassword = servicenow.password;
var ticketNo = "00000";

console.log(
  "Service Now URL:" +
    snowURL +
    " Username:" +
    snowUsername +
    " Password:" +
    snowPassword
);

module.exports = {
  createIncident: function(caller_id, short_description, callback) {
    var snowdetails = {
      uri: snowURL,
      json: {
        short_description: short_description
      },
      method: "POST",
      auth: {
        username: snowUsername,
        password: snowPassword
      }
    };

    request(snowdetails)
      .then(function(body) {
        var data = JSON.parse(JSON.stringify(body));
        ticketNo = data.result.number;
        console.log("Service Now Incident No:" + ticketNo);
        callback(ticketNo);
      })
      .catch(function(err) {
        console.log(err);
      });
  }
};

当我运行这个程序时，我得到的输出是

Service Now URL:myUrl 
Username:myUserName Password:myPassword
done
Service Now Incident No:INC0010107
Index.js ServiceNow Incident:INC0010107
end of flow

但根据流程，我需要输出为。

Service Now URL:myUrl
Username:myUserName Password:myPassword
Service Now Incident No:INC0010107
Index.js ServiceNow Incident:INC0010107
end of flow
done

我知道这与回调和 promise 有关，但不知道如何做。请帮助我了解我应该更改什么以获得流程中的输出(done 作为最后一件事打印)

Answer 1

打印 done 的控制台语句不在回调中，因此在调用 service.createIncident 后立即执行。

很容易修复，只需将日志语句移到回调中即可:

function dispatch() {
    const op = service.createIncident("enterpriseID", "shortDesc",
        function (incidentNo) {
            if (incidentNo) {
                console.log("Index.js ServiceNow Incident:" + incidentNo);
                var msg = "Thank you! Your  Number is " + incidentNo;
                console.log("end of flow");
            } else {
                console.log("Index.js ServiceNow Incident:" + incidentNo);
                msg = "Err";
                console.log("end of flow");
            }
            console.log("done");
        }
    );
}